Yeah remi/flan isn't actually all that hard if you know how to ambush. I find their 2nd card to be moderately difficult though because I haven't bothered to try and memorize remi's attack patterns. So sometimes she'll just nail me. You really can't avoid that attack without knowing where exactly she's going to go in advance..
Card 3 can be pretty hard at first with 4 flans, but once you take one out it's pretty easy..
I really hate the 4th card though (which is boring as @%@#% on any difficulty but lunatic, where it suddenly becomes difficult again. you can't just camp the bottom of the screen running left to right on lunatic, you have to go flying up and down and around and such. It's still not hard per say, but it's definately not a freebie). But anyway, I really hate the 4th card because I like to open up my combos with marissa doing a hit hit,downhit, dragonpunch, smackdown, change combo. But for some reason with this spellcard on this boss only.. She moves forward too much on the first two hits, and then my 3rd swooshes. So I end up having to wait another @%#@#%ing 3 hours for them to land. sighhh.